Right Quenchcrack, freshman year engineering consisted of two computer courses, binary and basic. I chose a different path. I did not touch a keyboard for most of my life, reasoning that knowlegde is like a pie and the less slices you try to take, the bigger your one slice will be. The slice I chose was metal. Finaly, with the developments of windows and the internet, the computer became too good of a tool to ignore, so now I am here, trying to add to its usefullness, and continue my education. But I digress, let us now analyse; Mike brought up h-13, a member of the chromium hot work group. These are deep hardening steels, which will essentialy harden all the way through, in small enough sections, IF HELD at critical plus, for soficient time for the heat to travel all the way through, also known as soak time or soaking heat. Whatever tool you are hardening, including knives need sufficient soak time. Thin or heavily machined metal require great care, skill, or knowledge to properly heat treat. This is what Quenchcrack meant when he said anybody can send it out and get it heat treated. The easiest and arguably best way to heat treat metal is in an oven designed for that purpose. However, most needs of the blacksmith can be met with a forge. The only caveat with air hardening alloys is that normalizing ( heating to the upper critical limit, soaking, allowing to cool in air, also known as open air annealing) will cause complete and total hardness. Which brings us to Evfreak. Even h-13 has a limit as to how red-hard it really is. Frequent cooling with water will entend, the work time, work capacity and life span of tools made from the chromium hotwork group. It is also tough enough to be quenched in water, but that is not nessasary. Are you sure it was at it's upper critical temp, or more, and had sufficient time at soak?. Plus it may not be air hard. High carbon tools, while very hardenable, can require frequent dressing and rehardening. That is why air hardening allows were developed. Which brings up to hunt for steel, which is different from gathering steel. When gathering steel, we must be armed with methods, tests if you will, to closely guess their properties. Hunting, is different. We determine the alloy we wish to aquire, by use of a list from a book, which lists all the different alloys of tool steel, and most of the items ever made from said alloy. Then we deduce, from that list, what object, near or available to us, is made from that alloy. Such lists are available in many comprehensive metalworking books, but much more detailed and complete in certain books such as those published by the American Society fo Metals(ASM), but also, ASTM,SAE, you get the idea. The advantage to this technique, is that the information for optimum heat treating becomes a known. Next week, using gathered steel.
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